Cauda Equina Syndrome

nerve roots
Fig 1: Spine nerve roots
(larger view)

Cauda equina syndrome is a relatively rare but serious condition that describes extreme pressure and swelling of the nerves at the end of the spinal cord. It gets its name from Latin,"horse’s tail," because the nerves at the end of the spine visually resemble a horse’s tail as they extend from the spinal cord down the back of each leg.

Cauda equina syndrome is a serious medical emergency that requires testing and possibly urgent surgical intervention. If patients with cauda equina syndrome do not get treatment quickly, adverse results can include permanent paralysis, impaired bladder and/or bowel control, difficulty walking, and/or other neurological and physical problems.

Cauda Equina Syndrome Causes

Cauda equina syndrome is caused by the compression of nerves in the lumbar spine and a narrowing of the spinal canal. This pressure on the spinal nerves can occur from several underlying causes, including:

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  • Spinal tumors that can put pressure on the nerves in the lower spine, such as neoplasms
  • Injury that penetrates the lower back, such as a gunshot or knife wound
  • Trauma to the lumbar spine, such as a car accident, fall, or surgery.

Cauda Equina Syndrome Symptoms

Typical symptoms of cauda equina syndrome are variable in intensity and onset, and may include one or more of the following:

  • Altered sensation, or severe or progressive weakness or numbness in the lower extremities, the legs and/or feet, possibly making it difficult to walk
  • Loss of sensation or a strange sensation in the "saddle" area (the area of the body that would sit on a saddle: inner thighs/between the legs, buttocks, back of legs, sacral region)
  • Urinary or bowel incontinence, including any dysfunction that causes retention of urine, inability to hold urine in, or loss of rectal control
  • Lower back pain, which may be described as an aching pain in a localized area
  • Sharp stabbing pain in the leg.

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Symptoms of cauda equina syndrome can occur suddenly or more gradually, developing over a few weeks or a few years.

  • Sudden onset. Symptoms of the sudden onset of cauda equina syndrome are typically marked by bladder and/or bowel incontinence or dysfunction and/or progressive weakness in the legs and/or feet.
  • Gradual onset. Symptoms of the gradual onset of cauda equina syndrome typically include recurring back pain in combination with muscle weakness and numbness and bladder and/or bowel incontinence or dysfunction.

Patients with any of the above symptoms should seek immediate medical attention.

Cauda Equina Syndrome Treatment

This condition typically requires emergency surgical decompression as quickly as possible in order to reduce or eliminate pressure on the nerve. Although there is no prospective randomized trial to confirm without a doubt, it is generally thought that surgery within 24 to 48 hours gives the maximum potential for improvement of sensory and motor deficits as well as bladder and bowel functioning, and most surgeons recommend surgery to decompress the nerves as soon as possible, within about 8 hours of onset of symptoms.1

The prognosis for cauda equina syndrome depends on a variety of factors, including the degree of nerve damage and how quickly the nerve is decompressed. Following surgery, the extent of the recovery is variable, and patients may continue to have some pain, problems with their bladder or bowel, and other dysfunctions depending on the duration and severity of symptoms prior to surgery.

Patients should be aware that acute cauda equina syndrome that results in nerve damage is extremely rare.


  1. Cauda equina syndrome secondary to lumbar disc herniation: a meta-analysis of surgical outcomes. Ahn UM, Ahn NU, Buchowski JM, Garrett ES, Sieber AN, Kostuik JP. Spine (Phila Pa 1976). 2000 Jun 15;25(12):1515-22.
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